Method of gaming, a gaming system and a game controller

ABSTRACT

A method of gaming comprising: selecting a plurality of symbols for display in a set of display positions on a display in each game round; initiating a series of one or more bonus game rounds conferring a special benefit on the player in response to a trigger condition being met; determining a game round outcome of whether to make an award to a player based on each game round; and ending the series of one or more bonus game rounds when less than a designated number of the displayed symbols in a subsequent game round is a bonus game symbol.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority to AustralianProvisional Patent Application No. 2007906649, filed on Dec. 5, 2007,and Australian Provisional Patent Application No. 2008901059, filed onMar. 4, 2008, each of which is herein incorporated by reference in itsentirety.

FIELD

The present invention relates to a method of gaming, a gaming system anda game controller.

BACKGROUND TO THE INVENTION

Gaming systems are known comprising a game controller arranged torandomly display several symbols from a predetermined set of symbols andto determine a game outcome such as a game win based on the displayedsymbols. Such gaming systems may commonly be implemented as a steppermachine provided with reels with each reel carrying several symbols ofthe set, or a video machine with selected symbols are displayed invirtual reels on a video display.

In such gaming systems it is known to provide a bonus game round or aseries of bonus game rounds on the occurrence of a trigger event. Abonus game round is provided without charge or otherwise conferring somespecial benefit to the player over and above the non-bonus game round.

While such bonus game round systems provide users with enjoyment, thereis a need for alternative gaming systems with different bonus gamefeatures.

SUMMARY OF THE INVENTION

In a first aspect, the invention provides a method of gaming including:

selecting a plurality of symbols for display in a set of displaypositions on a display in each game round;

initiating a series of one or more bonus game rounds conferring aspecial benefit on the player in response to a trigger condition beingmet;

determining a game round outcome of whether to make an award to a playerbased on each game round; and

ending the series of one or more bonus game rounds when less than adesignated number of the displayed symbols in a subsequent game round isa bonus game symbol.

In an embodiment, the trigger condition is that at least one of thedisplayed symbols is a bonus game symbol

In an embodiment, the designated number is one such that the series endswhen none of the displayed symbols in a subsequent game round is a bonusgame symbol

In an embodiment, the method further includes selecting the appearanceof the bonus game symbol randomly.

In an embodiment, the method further includes causing the disappearanceof the bonus game symbol randomly.

In an embodiment, the special benefit conferred on the player by thepresence of the bonus game symbol is that the next game round is free ofcharge.

In an embodiment, at each display position associated with a bonus gamesymbol, only the bonus game symbol is displayed.

In an embodiment, the bonus game symbol is a wild symbol able tosubstitute for any of the other displayed symbols in determining thegame round outcome.

In an embodiment, the bonus game symbols are displayed in conjunctionwith a normal symbol in the same display position.

In an embodiment, the method includes determining a displacement of eachbonus game symbol relative to the bonus game symbol's current displayposition such that if the displacement is to a display position withinthe set of display positions the series of bonus game rounds continuesand if the displacement is not to one of the set of display positionsand there are less than a designated number of bonus symbols after thedisplacement, the series of bonus game rounds ends.

In an embodiment, the displacement is randomly selected from a set ofpossible displacements relative to the previous display position.

In an embodiment, the set of display positions are a set of reel windowsset side by side each including a plurality of visible reel positions.

In an embodiment, the set of possible displacements is up or down withina reel, left or right between reels or a combination thereof.

In an embodiment, the displacement is not randomly selected.

In an embodiment, there is more than one bonus game symbol.

In a second aspect, the invention provides a gaming system including:

a display for symbols to be displayed in a set of display positions to aplayer;

a symbol selector arranged to select the symbols for display in eachgame round;

a bonus game controller arranged to: initiate a series of bonus gamerounds when a trigger condition is met, control the series of one ormore bonus game rounds, and end the series of bonus game rounds whenless than a designated number of the displayed symbols is a bonus gamesymbol; and

an outcome generator arranged to determine an outcome for each gameround.

In an embodiment, the bonus game controller is arranged to control theposition of each bonus game symbol during the series of one or morebonus game rounds.

In an embodiment, the bonus game controller includes a displacementselector to select a displacement of the bonus game symbol, whichdepending on the selected displacement, may or may not result in thebonus game symbol being displayed within the set of display positions.

In an embodiment, the displacement selector selects the displacementsrandomly from a set of possible displacements.

In an embodiment, the bonus game symbol is a wild symbol able tosubstitute for any or some of the other displayed symbols in determiningthe game round outcome.

In an embodiment, the trigger condition is that at least one of thedisplayed symbols is a bonus game symbol

In an embodiment, the designated number is one such that the series endswhen none of the displayed symbols in a subsequent game round is a bonusgame symbol

In an embodiment, the special benefit conferred on the player by thepresence of the bonus game symbol is that the next game round is free ofcharge.

In an embodiment, the set of display positions are a set of reel windowsset side by side each including a plurality of visible reel positions.

In an embodiment, the set of possible displacements is up or down withina reel, left or right between reels or a combination thereof.

In an embodiment, at least the game controller is implemented by aprocessor executing program code stored in a memory.

In an embodiment, the gaming system includes a game play mechanismoperable by the player to initiate a play of a game including at leastone initial game round and any bonus game rounds.

In a third aspect, the invention provides a game controller including:

a symbol selector arranged to select symbols for display to a player ineach of a plurality of game rounds;

a bonus game controller arranged to initiate a series of bonus gamerounds when a trigger condition is met, to control the series of one ormore bonus game rounds, and to end the series of bonus game rounds whenless than a designated number of the displayed symbols is a bonus gamesymbol; and

an outcome generator arranged to determine an outcome for each gameround based on each game round.

In an embodiment, the bonus game controller is arranged to control theposition of each bonus game symbol during the series of one or morebonus game rounds.

In an embodiment, the bonus game controller includes a displacementselector to select a displacement of the bonus game symbol, whichdepending on the selected displacement, may or may not result in thebonus game symbol being displayed within the set of display positions.

In an embodiment, the displacement selector is arranged to select thedisplacements randomly from a set of possible displacements.

In an embodiment, the bonus game symbol is a wild symbol able tosubstitute for any or some of the other displayed symbols in determiningthe game round outcome.

In an embodiment, the trigger condition is that at least one of thedisplayed symbols is a bonus game symbol

In an embodiment, the designated number is one such that the series endswhen none of the displayed symbols in a subsequent game round is a bonusgame symbol

In an embodiment, the special benefit conferred on the player by thepresence of the bonus game symbol is that the next game round is free ofcharge.

In an embodiment, the game controller is implemented by a processorexecuting program code stored in a memory.

In a fourth aspect, there is provided computer program code which whenexecuted by a computer causes the computer to implement the method ofthe first aspect.

In a fifth aspect, the invention provides a computer readable mediumincluding the above program code.

In a sixth aspect, the invention provides a data signal including theabove program code.

In a seventh aspect, the invention extends to transmitting the programcode.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of the core components of a gaming system.

FIG. 2 is a perspective view of a stand alone gaming machine;

FIG. 3 is a block diagram of the functional components of a gamingmachine;

FIG. 4 is a schematic diagram of the functional components of a memory;

FIG. 5 is a schematic diagram of a network gaming system;

FIG. 6 is a further block diagram of the gaming system;

FIGS. 7A to 7D show displays of an example;

FIG. 8 shows a flow diagram for the example.

The foregoing summary, as well as the following detailed description ofcertain embodiments of the present invention, will be better understoodwhen read in conjunction with the appended drawings. For the purpose ofillustrating the invention, certain embodiments are shown in thedrawings. It should be understood, however, that the present inventionis not limited to the arrangements and instrumentality shown in theattached drawings.

DETAILED DESCRIPTION

Referring to the drawings, there is shown a gaming system arranged toimplement a game wherein a trigger condition such as a bonus game symbolappearing, starts a series of bonus game rounds involving the bonus gamesymbol. When the bonus game symbol disappears, this ends the series. Thegaming system can take a number of different forms.

In a first form, a stand alone gaming machine is provided wherein all ormost components for implementing the game are present in a playeroperable gaming machine.

In a second form, a distributed architecture is provided wherein some ofthe components for implementing the game are present in a playeroperable gaming machine and some of the components for implementing thegame are located remotely relative to the gaming machine. For example, a“thick client” architecture may be used wherein part of the game isexecuted on a player operable gaming machine and part of the game isexecuted remotely, such as by a gaming server; or a “thin client”architecture may be used wherein most of the game is executed remotelysuch as by a gaming server and a player operable gaming machine is usedonly to display audible and/or visible gaming information to the playerand receive gaming inputs from the player.

However, it will be understood that other arrangements are envisaged.For example, an architecture may be provided wherein a gaming machine isnetworked to a gaming server and the respective functions of the gamingmachine and the gaming server are selectively modifiable. For example,the gaming system may operate in stand alone gaming machine mode, “thickclient” mode or “thin client” mode depending on the game being played,operating conditions, and so on. Other variations will be apparent topersons skilled in the art.

Irrespective of the form, the gaming system includes several corecomponents. At the broadest level, the core components are a playerinterface 50 and a game controller 60 as illustrated in FIG. 1. Theplayer interface is arranged to enable manual interaction between aplayer and the gaming system and for this purpose includes theinput/output components for the player to enter instructions and playthe game.

Components of the player interface may vary from embodiment toembodiment but will typically include a credit mechanism 52 to enable aplayer to input credits and receive payouts, one or more displays 54, agame play mechanism 56 that enables a player to input game playinstructions (e.g. to place bets), and one or more speakers 58.

The game controller 60 is in data communication with the playerinterface and typically includes a processor 62 that processes the gameplay instructions in accordance with game play rules and outputs gameplay outcomes to the display. Typically, the game play instructions arestored as program code in a memory 64 but can also be hardwired. Hereinthe term “processor” is used to refer generically to any device that canprocess game play instructions in accordance with game play rules andmay include: a microprocessor, microcontroller, programmable logicdevice or other computational device, a general purpose computer (e.g. aPC) or a server.

A gaming system in the form of a stand alone gaming machine 10 isillustrated in FIG. 2. The gaming machine 10 includes a console 12having a display 14 on which are displayed representations of a game 16that can be played by a player. A mid-trim 20 of the gaming machine 10houses a bank of buttons 22 for enabling a player to interact with thegaming machine, in particular during game play. The mid-trim 20 alsohouses a credit input mechanism 24 which in this example includes a coininput chute 24A and a bill collector 24B. Other credit input mechanismsmay also be employed, for example, a card reader for reading a smartcard, debit card or credit card. A player marketing module (not shown)having a reading device may also be provided for the purpose of readinga player tracking device, for example as part of a loyalty program. Theplayer tracking device may be in the form of a card, flash drive or anyother portable storage medium capable of being read by the readingdevice.

A top box 26 may carry artwork 28, including for example pay tables anddetails of bonus awards and other information or images relating to thegame. Further artwork and/or information may be provided on a frontpanel 29 of the console 12. A coin tray 30 is mounted beneath the frontpanel 29 for dispensing cash payouts from the gaming machine 10.

The display 14 shown in FIG. 2 is in the form of a video display unit,particularly a cathode ray tube screen device. Alternatively, thedisplay 14 may be a liquid crystal display, plasma screen, any othersuitable video display unit, or the visible portion of anelectromechanical device. The top box 26 may also include a display, forexample a video display unit, which may be of the same type as thedisplay 14, or of a different type.

FIG. 3 shows a block diagram of operative components of a typical gamingmachine which may be the same as or different to the gaming machine ofFIG. 2.

The gaming machine 100 includes a game controller 101 having a processor102. Instructions and data to control operation of the processor 102 arestored in a memory 103, which is in data communication with theprocessor 102. Typically, the gaming machine 100 will include bothvolatile and non-volatile memory and more than one of each type ofmemory, with such memories being collectively represented by the memory103.

The gaming machine has hardware meters 104 for purposes includingensuring regulatory compliance and monitoring player credit, aninput/output (I/O) interface 105 for communicating with peripheraldevices of the gaming machine 100. The input/output interface 105 and/orthe peripheral devices may be intelligent devices with their own memoryfor storing associated instructions and data for use with theinput/output interface or the peripheral devices. A random numbergenerator module 113 generates random numbers for use by the processor102. Persons skilled in the art will appreciate that the reference torandom numbers includes pseudo-random numbers.

In the example shown in FIG. 3, a player interface 120 includesperipheral devices that communicate with the game controller 101 includeone or more displays 106, a touch screen and/or buttons 107, a cardand/or ticket reader 108, a printer 109, a bill acceptor and/or coininput mechanism 110 and a coin output mechanism 111. Additional hardwaremay be included as part of the gaming machine 100, or hardware may beomitted based on the specific implementation.

In addition, the gaming machine 100 may include a communicationsinterface, for example a network card 112. The network card may, forexample, send status information, accounting information or otherinformation to a central controller, server or database and receive dataor commands from the central controller, server or database.

FIG. 4 shows a block diagram of the main components of an exemplarymemory 103. The memory 103 includes RAM 103A, EPROM 103B and a massstorage device 103C. The RAM 103A typically temporarily holds programfiles for execution by the processor 102 and related data. The EPROM103B may be a boot ROM device and/or may contain some system or gamerelated code. The mass storage device 103C is typically used to storegame programs, the integrity of which may be verified and/orauthenticated by the processor 102 using protected code from the EPROM103B or elsewhere.

It is also possible for the operative components of the gaming machine100 to be distributed, for example input/output devices106,107,108,109,110,111 to be provided remotely from the game controller101.

FIG. 5 shows a gaming system 200 in accordance with an alternativeembodiment. The gaming system 200 includes a network 201, which forexample may be an Ethernet network. Gaming machines 202, shown arrangedin three banks 203 of two gaming machines 202 in FIG. 5, are connectedto the network 201. The gaming machines 202 provide a player operableinterface and may be the same as the gaming machines 10,100 shown inFIGS. 2 and 3, or may have simplified functionality depending on therequirements for implementing game play. While banks 203 of two gamingmachines are illustrated in FIG. 5, banks of one, three or more gamingmachines are also envisaged.

One or more displays 204 may also be connected to the network 201. Forexample, the displays 204 may be associated with one or more banks 203of gaming machines. The displays 204 may be used to displayrepresentations associated with game play on the gaming machines 202,and/or used to display other representations, for example promotional orinformational material.

In a thick client embodiment, game server 205 implements part of thegame played by a player using a gaming machine 202 and the gamingmachine 202 implements part of the game. With this embodiment, as boththe game server and the gaming device implement part of the game, theycollectively provide a game controller. A database management server 206may manage storage of game programs and associated data for downloadingor access by the gaming devices 202 in a database 206A. Typically, ifthe gaming system enables players to participate in a Jackpot game, aJackpot server 207 will be provided to perform accounting functions forthe Jackpot game. A loyalty program server 212 may also be provided.

In a thin client embodiment, game server 205 implements most or all ofthe game played by a player using a gaming machine 202 and the gamingmachine 202 essentially provides only the player interface. With thisembodiment, the game server 205 provides the game controller. The gamingmachine will receive player instructions, pass these to the game serverwhich will process them and return game play outcomes to the gamingmachine for display. In a thin client embodiment, the gaming machinescould be computer terminals, e.g. PCs running software that provides aplayer interface operable using standard computer input and outputcomponents.

Servers are also typically provided to assist in the administration ofthe gaming network 200, including for example a gaming floor managementserver 208, and a licensing server 209 to monitor the use of licensesrelating to particular games. An administrator terminal 210 is providedto allow an administrator to run the network 201 and the devicesconnected to the network.

The gaming system 200 may communicate with other gaming systems, otherlocal networks, for example a corporate network, and/or a wide areanetwork such as the Internet, for example through a firewall 211.

Persons skilled in the art will appreciate that in accordance with knowntechniques, functionality at the server side of the network may bedistributed over a plurality of different computers. For example,elements may be run as a single “engine” on one server or a separateserver may be provided. For example, the game server 205 could run arandom generator engine. Alternatively, a separate random numbergenerator server could be provided. Further, persons skilled in the artwill appreciate that a plurality of games servers could be provided torun different games or a single game server may run a plurality ofdifferent games based on the terminals.

The game controllers of gaming systems implementing games that involve adisplay of spinning reels as part of the display of the outcome of thegame have a stop determining function that determines the stop positionfor each reel. For example, if there are five reels, each having twentysymbols, the stop determining function might determine that the stoppositions are positions: 3, 13, 7, 9 and 17. The spinning of the reelsis then controlled so that each symbol comes to a stop in the same row,typically a designated row in a “window”, the designated rowcorresponding to a “single win line” game. When the reels stops, thesymbols will be in one of a plurality of possible symbol positions forthat reel relative to the stop position.

Embodiments of the present invention include gaming systems that allow aplayer to select how many win lines of a plurality of win lines theywill play in each game—i.e. a minimum of one win line up to the maximumnumber of win lines allowed by the game. Each win line is formed by aset of symbol positions consisting of one symbol position from eachreel. That is, a predetermined symbol position of each reel is assignedto a win line. The symbol positions that constitute each of the winlines are usually advertised to the player by markings on the display ordiagrams showing the symbol positions that correspond to each win line.The win lines may be for example, horizontal or diagonal lines.

The game controller of an embodiment is shown in more detail in FIG. 6.The game controller carries out a play of the game in response to aplayer operating a game play mechanism 56 to place a wager. The gamecontroller carries out an initial game round and, if a trigger conditionis met, one or more bonus game rounds. Each game round involves theselection of some fresh symbols. The game controller 60 incorporates asymbol selector 610 that selects symbols using random numbers fromrandom number generator 650 under control of outcome generator 630,including possibly a bonus game symbol, to appear on the display 54. Inthe embodiment, the appearance of a bonus game symbol in the initialgame round initiates a series of one or more bonus game rounds, howeverother triggers known in the art may be employed such as symbolcombination occurring, a turnover elapsing or a system connected to thegaming system triggering the bonus game series. During the series ofbonus game rounds, the symbol selector 610 operates to select furthersets of game symbols, and the bonus game controller 620 controls, viadisplacement selector 625, the new position, if any, of the bonus gamesymbol in the next game, using one of a set of possible displacementsfrom displacement data 646 such that it will replace the symbol selectedfor that position. If there is more than one bonus symbol, each iscontrolled. In this embodiment, the choice of displacement is made onthe basis of a random number provided by random number generator 650. Inanother alternative, the displacement is deterministic. The further setof symbols may include a further bonus symbol. The displacement selectormay be arranged so that the new position of a bonus symbol cannot overlyanother bonus symbol.

Once the bonus game rounds begin, the player will receive a specialbenefit for the next game round which in an embodiment is that the nextgame round is free. Another example of special benefit is that the prizefor the next game round is doubled. Another example, is that thepersistent bonus game symbol has an additional play characteristic whichconfers a benefit for example, a wild symbol increases the chances ofwinning outcomes occurring.

The outcome generator 630 includes an outcome evaluator 635 to calculateany prize associated with the current round depending on the gameinstructions 644 and updateprize data 645 and display 54 on the playerinterface 50. In an embodiment the bonus symbol is a wild symbol and cansubstitute for any normal symbol in evaluation of prizes specified bythe prize data 645.

On completion of the current round, the symbol selector 610 uses randomnumber generator 650 to generate a new symbol set for the next bonusgame round and passes control of the bonus game symbol to bonus gamesymbol controller 620. Bonus game symbol controller 620 determines usingdisplacement selector 625 where and whether on the display positions thebonus game symbol should appear and symbol selector 610 replaces thesymbol selected for that location with the bonus game symbol. As in theprevious round, the outcome generator 630 calculates the game roundoutcome and updates prize data 645.

The series of bonus game rounds ends when bonus game symbol controller620 produces a displacement that causes the bonus game symbol todisappear off the set of display positions. In embodiments, where thereis more than one bonus game symbol, typically all symbols are requiredto “disappear” before the series ends. However, alternative embodimentsare possible where a minimum number of symbols are required for theseries to continue such that the series may end with a bonus symbolstill displayed. That is, the game series is ended when less than adesignated number of bonus game symbols is displayed; the designatednumber may be 1, 2 or more (a value of 1 implying that no bonus gamesymbols are displayed). Once the bonus game rounds ends, the playerplaces a further wager to initiate another initial game round. Theplayer may be presented with options such as a “gamble” option at theconclusion of the game round and before credits are transferred to thecredit meter.

In an embodiment, the bonus game symbol is a single symbol and itoccupies the space of a normal symbol. In an alternative embodiment, thebonus game symbol appears with a normal symbol in the same position,with both symbols visible. This alternative embodiment allows additionaloptions for the effect of the bonus symbol according to the gameinstructions 644 on the prize data 645, such as a multiplier for anyprize calculated using the normal symbol in the same position.

It will be apparent from the above embodiment, that the bonus game roundconfers a benefit on the player, in the embodiment, that each bonus gameround is free and the player has improved opportunities by virtue of thewild symbol. In other embodiments, additional or different benefits maybe conferred, for example prizes may be multiplied.

During the series of bonus game rounds, random selection of a newdisplay position for the bonus game symbol is made by the new positionselector 625. When this selection is made by a displacement based on aset of possible displacements in displacement data 646, the displacementmay be restricted to a random choice among the set of possibledisplacements. For example, a “dance step” such as two positions up andone across.

The displacement of the bonus game symbols can be displayed in a numberof different styles, for example:

“walking”, “dancing”, “jumping” or “sliding” the symbol from oneposition to the next prior to the reels spinning in the next game;

“walking”, “dancing”, “jumping” or “sliding” the symbol from oneposition to the next as the reels are spinning in the next game;

“walking”, “dancing”, “jumping” or “sliding” the symbol from oneposition to the next after the reels have spun in the next game; or

visually disappearing as the reels are spun and reappearing as the reelsstop spinning.

The method 80 of an embodiment of the invention is summarised in FIG. 8.The method involves starting the game 810 and determining 820 whetherthis is a bonus game round. If it is not a bonus game round (as will bethe case initially,) the method involves selecting all symbols fordisplay and their positions 830.

The method then involves determining the game round outcome 840 andawarding any prizes associated with the game outcome. It is thendetermined 870 whether one of the symbols that has been selected is abonus game symbol. If it is a bonus game symbol a series of bonus gamerounds is initiated 890 such that in the second iteration, the answer at820 will be that it is a bonus game round and hence non-bonus symbolswill be selected and the new position or appearance of the bonus gameround symbol will be determined. The game outcome will then bedetermined with the method continuing to step 870 where after if one ofthe symbols is a bonus symbol, the game will continue, otherwise theseries of bonus game rounds ends.

In an alternative embodiment, an alternative or additionaltransformation may be applied to the bonus symbol between game rounds.For example, the colour of the bonus symbol may be changed from red toblue to indicate that it has persisted from a previous round or a set ofdifferent bonus symbols may be employed indicative of the longevity ofthe symbol.

Game Round 1 Example

Now referring to FIG. 7A, a player has purchased a game round or is inan existing series of bonus game rounds and the symbols shown appear onthe reels. The display is divided into 5 reels 740 a to 740 e eachdisplaying 3 symbols in the window, in rows 750 a, 750 b and 750 c. Thebonus game symbol marked W indicates that next game round will be abonus game round. The bonus game symbol W is a wild symbol, enablingsubstitution with normal symbols, but in this case there are no patternswith any such substitution which the outcome generator 630 determinescan win a prize and so the prize data 645 is not updated.

Game Round 2 Example

This game, following from Game Round 1, is free because the W symbols isin the windom. As shown in FIG. 7B, the symbol selector 610 has selecteda new set of symbols to display and the bonus game controller 620 hasdetermined using displacement selector 625 a displacement from W of onerow down in the same reel, into the centre row, covering the symbolwhich would have appeared on the fourth reel, centre. The outcomegenerator 630 awards the prize for four Kings (“K”) on the centre row,as if W were a King, and the prize data 645 is updated.

Game Round 3 Example

This game, following from Game Round 2 where the bonus game symbol stillappeared, is still part of the bonus game round series and is free. Asshown in FIG. 7 c, the symbol selector 610 has selected a new set ofsymbols to display and the bonus game symbol controller has determined anew position for the bonus game symbol W in the third reel in the bottomrow, a displacement of 1 row down and one reel left from the previousgame, covering the symbol which would have appeared on the third reel,lower. There are no patterns with any wild symbol substitution for Wwhich the outcome generator 630 determines can win a prize and so theprize data 645 is not updated. Because the bonus game symbol is stillpresent, the next game round (Game Round 4) will also be free.

Game Round 4 Example

This game, following from game round 3 where the bonus game symbol stillappeared, is still part of the bonus game round series and is free. Asshown in FIG. 7 d, the symbol selector 610 has selected a new set ofnon-bonus symbols to display and the displacement selector 625 hasselected a displacement down one further row, off the display. No symbolpositions are replaced and the bonus game symbol will not appear. Theoutcome generator 630 determines that there are no winning patterns andso the prize data 645 is not updated. Because the bonus game symbol isnot displayed, the series of bonus game rounds ends and the next gameround will not be free.

Persons skilled in the art will appreciate that the method of anembodiment could be embodied in program code. The program code could besupplied in a number of ways, for example on a computer readable medium,such as a disc or a memory (for example, that could replace part ofmemory 103) or as a data signal (for example, by downloading it from aserver).

Persons skilled in the art will also appreciate that many variations maybe made to the invention without departing from the scope of theinvention. In particular, features of the above embodiment and examplesmay be combined to form further embodiments.

In the claims which follow and in the preceding description of theinvention, except where the context indicates otherwise due to expresslanguage or necessary implication, the word “comprise” or variationssuch as “comprises” or “comprising” is used in an inclusive sense, i.e.to specify the presence of the stated features but not to preclude thepresence or addition of further features in various embodiments of theinvention.

Modifications and variations as would be apparent to a skilled addresseeare deemed to be within the scope of the present invention.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive. Several embodiments are described above with reference tothe drawings. These drawings illustrate certain details of specificembodiments that implement the systems and methods and programs of thepresent invention. However, describing the invention with drawingsshould not be construed as imposing on the invention any limitationsassociated with features shown in the drawings. The present inventioncontemplates methods, systems and program products on any electronicdevice and/or machine-readable media suitable for accomplishing itsoperations. Certain embodiments of the present invention may beimplemented using an existing computer processor and/or by a specialpurpose computer processor incorporated for this or another purpose orby a hardwired system, for example.

Embodiments within the scope of the present invention include programproducts comprising machine-readable media for carrying or havingmachine-executable instructions or data structures stored thereon. Suchmachine-readable media can be any available media that can be accessedby a general purpose or special purpose computer or other machine with aprocessor. By way of example, such machine-readable media may compriseRAM, ROM, PROM, EPROM, EEPROM, Flash, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium which can be used to carry or store desired program code inthe form of machine-executable instructions or data structures and whichcan be accessed by a general purpose or special purpose computer orother machine with a processor. When information is transferred orprovided over a network or another communications connection (eitherhardwired, wireless, or a combination of hardwired or wireless) to amachine, the machine properly views the connection as a machine-readablemedium. Thus, any such a connection is properly termed amachine-readable medium. Combinations of the above are also includedwithin the scope of machine-readable media. Machine-executableinstructions comprise, for example, instructions and data which cause ageneral purpose computer, special purpose computer, or special purposeprocessing machines to perform a certain function or group of functions.

Method steps associated with certain embodiments may be implemented inone embodiment by a program product including machine-executableinstructions, such as program code, for example in the form of programmodules executed by machines in networked environments. Generally,program modules include routines, programs, objects, components, datastructures, etc., that perform particular tasks or implement particularabstract data types. Machine-executable instructions, associated datastructures, and program modules represent examples of program code forexecuting steps of the methods disclosed herein. The particular sequenceof such executable instructions or associated data structures representsexamples of corresponding acts for implementing the functions describedin such steps.

1. A method of gaming comprising: selecting a plurality of symbols fordisplay in a set of display positions on a display in each game round;initiating a series of one or more bonus game rounds conferring aspecial benefit on the player in response to a trigger condition beingmet; determining a game round outcome of whether to make an award to aplayer based on each game round; and ending the series of one or morebonus game rounds when less than a designated number of the displayedsymbols in a subsequent game round is a bonus game symbol.
 2. A methodas claimed in claim 1, wherein the trigger condition is that at leastone of the displayed symbols is a bonus game symbol
 3. A method asclaimed in claim 1, wherein the designated number is one such that theseries ends when none of the displayed symbols in a subsequent gameround is a bonus game symbol
 4. A method as claimed in claim 2, furthercomprising selecting the appearance of the bonus game symbol randomly.5. A method as claimed in claim 3, further comprising causing thedisappearance of the bonus game symbol randomly.
 6. A method as claimedin claim 1, wherein the special benefit conferred on the player by thepresence of the bonus game symbol is that the next game round is free ofcharge.
 7. A method as claimed in claim 1, wherein at each displayposition associated with a bonus game symbol, only the bonus game symbolis displayed.
 8. A method as claimed in claim 7, wherein the bonus gamesymbol is a wild symbol able to substitute for any of the otherdisplayed symbols in determining the game round outcome.
 9. A method asclaimed in claim 1, wherein the bonus game symbols are displayed inconjunction with a normal symbol in the same display position.
 10. Amethod as claimed in claim 1, comprising determining a displacement ofeach bonus game symbol relative to the bonus game symbol's currentdisplay position such that if the displacement is to a display positionwithin the set of display positions the series of bonus game roundscontinues and if the displacement is not to one of the set of displaypositions and there are less than a designated number of bonus symbolsafter the displacement, the series of bonus game rounds ends.
 11. Amethod as claimed in claim 10, wherein the displacement is randomlyselected from a set of possible displacements relative to the previousdisplay position.
 12. A method as claimed in claim 10, wherein the setof display positions are a set of reel windows set side by side eachcomprising a plurality of visible reel positions.
 13. A method asclaimed in claim 12, wherein the set of possible displacements is up ordown within a reel, left or right between reels or a combinationthereof.
 14. A method as claimed in claim 10, wherein the displacementis not randomly selected.
 15. A method as claimed in claim 1, whereinthere is more than one bonus game symbol.
 16. A gaming systemcomprising: a display for symbols to be displayed in a set of displaypositions to a player; a symbol selector arranged to select the symbolsfor display in each game round; a bonus game controller arranged to:initiate a series of bonus game rounds when a trigger condition is met,control the series of one or more bonus game rounds, and end the seriesof bonus game rounds when less than a designated number of the displayedsymbols is a bonus game symbol; and an outcome generator arranged todetermine an outcome for each game round.
 17. A gaming system as claimedin claim 16, wherein the bonus game controller is arranged to controlthe position of each bonus game symbol during the series of one or morebonus game rounds.
 18. A gaming system as claimed in claim 17, whereinthe bonus game controller comprises a displacement selector to select adisplacement of the bonus game symbol, which depending on the selecteddisplacement, may or may not result in the bonus game symbol beingdisplayed within the set of display positions.
 19. A gaming system asclaimed in claim 17, wherein the displacement selector selects thedisplacements randomly from a set of possible displacements.
 20. Agaming system as claimed in claim 16, wherein the bonus game symbol is awild symbol able to substitute for any or some of the other displayedsymbols in determining the game round outcome.
 21. A gaming system asclaimed in claim 16, wherein the trigger condition is that at least oneof the displayed symbols is a bonus game symbol
 22. A gaming system asclaimed in claim 16, wherein the designated number is one such that theseries ends when none of the displayed symbols in a subsequent gameround is a bonus game symbol
 23. A gaming system as claimed in claim 16,wherein the special benefit conferred on the player by the presence ofthe bonus game symbol is that the next game round is free of charge. 24.A gaming system as claimed in claim 16, wherein the set of displaypositions are a set of reel windows set side by side each comprising aplurality of visible reel positions.
 25. A gaming system as claimed inclaim 24, wherein the set of possible displacements is up or down withina reel, left or right between reels or a combination thereof.
 26. Agaming system as claimed in claim 16, wherein at least the gamecontroller is implemented by a processor executing program code storedin a memory.
 27. A gaming system as claimed in claim 16, comprising agame play mechanism operable by the player to initiate a play of a gamecomprising at least one initial game round and any bonus game rounds.28. A game controller comprising: a symbol selector arranged to selectsymbols for display to a player in each of a plurality of game rounds; abonus game controller arranged to initiate a series of bonus game roundswhen a trigger condition is met, to control the series of one or morebonus game rounds, and to end the series of bonus game rounds when lessthan a designated number of the displayed symbols is a bonus gamesymbol; and an outcome generator arranged to determine an outcome foreach game round based on each game round.
 29. A game controller asclaimed in claim 29, wherein the bonus game controller is arranged tocontrol the position of each bonus game symbol during the series of oneor more bonus game rounds.
 30. A game controller as claimed in claim 29,wherein the bonus game controller comprises a displacement selector toselect a displacement of the bonus game symbol, which depending on theselected displacement, may or may not result in the bonus game symbolbeing displayed within the set of display positions.
 31. A gamecontroller as claimed in claim 30, wherein the displacement selector isarranged to select the displacements randomly from a set of possibledisplacements.
 32. A game controller as claimed in claim 28, wherein thebonus game symbol is a wild symbol able to substitute for any or some ofthe other displayed symbols in determining the game round outcome.
 33. Agame controller as claimed in claim 28, wherein the trigger condition isthat at least one of the displayed symbols is a bonus game symbol
 34. Agame controller as claimed in claim 28, wherein the designated number isone such that the series ends when none of the displayed symbols in asubsequent game round is a bonus game symbol
 35. A game controller asclaimed in claim 28, wherein the special benefit conferred on the playerby the presence of the bonus game symbol is that the next game round isfree of charge.
 36. A game controller as claimed in claim 28,implemented by a processor executing program code stored in a memory.37. A computer readable medium including computer program code whichwhen executed by a computer causes a computer to implement a computerimplemented method of gaming, the method comprising: selecting aplurality of symbols for display in a set of display positions on adisplay in each game round; initiating a series of one or more bonusgame rounds conferring a special benefit on the player in response to atrigger condition being met; determining a game round outcome of whetherto make an award to a player based on each game round; and ending theseries of one or more bonus game rounds when less than a designatednumber of the displayed symbols in a subsequent game round is a bonusgame symbol.